Raman spectroscopic study of the effects of Ca2+, Mg2+, Zn2+, and Cd2+ ions on calf thymus DNA: binding sites and conformational changes.
The interaction of Mg2+, Ca2+, Zn2+, and Cd2+ with calf thymus DNA has been investigated by Raman spectroscopy. These spectra reveal that all of these ions, and particularly Zn2+, bind to phosphate groups of DNA, causing a slight structural change in the polynucleotide at very small metal: DNA (P) concentration ratio (ca. 1:30). This results in increased base-stacking interactions, with negligible change of the B conformation of DNA. Contrary to Zn2+ and Cd2+, which interact extensively with the nucleic bases (particularly at the N7 position of guanine), the alkaline-earth metal ions are bound almost exclusively to the phosphate groups. The affinity of both the Zn2+ and Cd2+ ions for G.C base pairs is comparable, but the Cd2+ ions interact more extensively with A.T pairs than Zn2+ ions. Interstrand cross-linking through the N3 atom of cytosine is suggested in the presence of Zn2+, but not Cd2+.
Langlais
M
M
Département de chimie, Université Laval, Québec, Canada.
Tajmir-Riahi
H A
HA
Savoie
R
R
D000818:Animals; D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D013059:Spectrum Analysis, Raman
D002104:Cadmium; D004247:DNA; D008274:Magnesium; D002118:Calcium